Fresh fish is to be transported long distances, for exampel by air, retaining a constant low temperature of approximately +2.degree. C. The fish is usually packed in boxes of insulating material, which are placed inside a cover of kraft liner board. As cooling medium ice is used, which gradually melts, whereby the water from the melted ice runs around the fish and cools the same.
Great demands are put on similar packings concerning density, especially if the fish should be transported together with other types of goods in connection with air transportations, where absolutely no leakage is permitted.